The Role of DLST in Leukemogenesis

项目总结 尽管治疗方法有所改进，但白血病相关死亡率仍然很高，原因是耐药性和 疾病复发。代谢重编程是癌症的一个标志，代表了一个令人兴奋的新领域 靶向治疗。因此，确定负责代谢重新编程的关键酶和 阐明其在耐药白血病细胞中的作用机制可能导致新的治疗方法 针对这些癌细胞独特的新陈代谢依赖性的策略。我们最近报道说 二氢硫胺S琥珀酰基转移酶(DLST)是MYC-MYC中一种关键的代谢“癌必需”酶。 导致白血病的发生。MYC依赖的T淋巴细胞白血病(T-ALL)细胞重编程代谢 通过稳定DLST蛋白，并严重依赖其高水平的增殖和生存。杂合子 斑马鱼中dlst的丢失不会损害发育，但显著延迟MYC诱导的T-ALL的发病 这类似于人类疾病的一个主要亚型，预后很差。DLST是细胞内的一种转移酶 三羧酸循环，并介导α-酮戊二酸(α-KG)转化为琥珀酰辅酶A。α-KG是 一种关键环中间体，同时作为α-KG依赖的必备辅因子 双加氧酶(α-KGDO，例如去甲基酶)，从而将细胞代谢与表观遗传控制联系起来。 手机。我们的假设是：DLST蛋白的稳定化加速了α-KG的转化，增强了TCA 循环功能，并抑制α-KGDO活性，从而促进白血病细胞增殖和 生死存亡。在本应用程序的目标1中，我们将应用遗传学、药理学和生物化学方法来 确定DLST在MYC过表达的T-ALL细胞中稳定的机制并鉴定新的 DLST相互作用因子，包括其E3连接酶(S)。然后将使用斑马鱼T-ALL模型来定义 T-ALL发病机制中关键的DLST调节因子/相互作用因子。在目标2中，我们将结合体内的分析 斑马鱼模型和人类T-ALL细胞鉴定与生化和表观遗传相关的变化 DLST失活，以及在T-ALL发病机制中受DLST调控的关键α-KGDO的功能特征。 在目标3中，我们将研究DLST在复发/难治性T-ALL中的靶向性和代偿途径 通过使用我们新发现的DLST抑制剂和包括小鼠患者来源的体内动物模型 异种移植物。这一应用的创新之处在于将DLST作为一种新型的癌必需酶进行研究 调节体内生理相关斑马鱼细胞的代谢和表观遗传状态 系统。事实上，这个创新的系统使我们能够识别MYC和AMP激活的蛋白激酶 DLST调节因子和异柠檬酸脱氢酶2作为其补偿基因。这项研究具有重要的意义 这将加深我们对白血病发病机制和癌症代谢的理解，以及 依赖MYC的白血病细胞中的代谢-表观遗传联系，长期目标是发展 针对癌细胞中DLST介导的通路的新治疗策略。

PROJECT SUMMARY Despite treatment improvements, leukemia-associated mortality is still high owing to drug resistance and disease relapse. Metabolic reprogramming is a hallmark of cancer, and represents an exciting new area of targeted therapy. Therefore, identification of the key enzyme responsible for metabolic reprogramming and elucidation of its mechanisms of action in treatment-resistant leukemic cells could lead to novel therapeutic strategies against the unique metabolic dependence of these cancer cells. We recently reported that dihydrolipoamide S-succinyltransferase (DLST) serves as a critical metabolic “oncorequisite” enzyme in MYC- driven leukemogenesis. MYC-dependent T-acute lymphoblastic leukemia (T-ALL) cells reprogram metabolism by stabilizing DLST protein, and rely heavily on its elevated levels for proliferation and survival. Heterozygous loss of dlst in zebrafish does not impair development yet significantly delays the onset of MYC-induced T-ALL that resembles a major subtype of human disease with poor prognosis. DLST is a transferase in the tricarboxylic acid (TCA) cycle and mediates the conversion of α-ketoglutarate (α-KG) to succinyl-CoA. α-KG is a key cycle intermediate that simultaneously functions as an obligatory cofactor for α-KG-dependent dioxygenases (α-KGDO, e.g., demethylases), thus linking cellular metabolism with epigenetic controls of the cell. We hypothesize that: DLST protein stabilization accelerates α-KG conversion, enhances TCA cycle function, and suppresses α-KGDO activities, thus promoting leukemic cell proliferation and survival. In Aim 1 of this application we will apply genetic, pharmacological and biochemical approaches to determine the mechanisms by which DLST is stabilized in MYC-overexpressing T-ALL cells and identify novel DLST interactors including its E3 ligase(s). The zebrafish T-ALL model will then be utilized to define the role of key DLST regulators/interactors in T-ALL pathogenesis. In Aim 2, we will combine the analyses of the in vivo zebrafish model and human T-ALL cells to identify the biochemical and epigenetic changes associated with DLST inactivation, as well as functionally characterize key α-KGDO regulated by DLST in T-ALL pathogenesis. In Aim 3, we will investigate the targetability and compensatory pathways of DLST in relapsed/refractory T-ALL by using our newly identified DLST inhibitor and in vivo animal models including murine patient-derived xenografts. The innovation of this application lies in the study of DLST as a novel “oncorequisite” enzyme that regulates both metabolism and epigenetic status of the cell in a physiologically relevant in vivo zebrafish system. Indeed, this innovative system has enabled us to identify MYC and AMP-activated protein kinase as regulators for DLST and isocitrate dehydrogenase 2 as its compensatory gene. This research is significant in that it will deepen our understanding of leukemia pathogenesis and cancer metabolism, as well as the metabolo-epigenetic connections in MYC-dependent leukemic cells, with the long-term goal of developing novel therapeutic strategies against DLST-mediated pathways in cancer cells.